Editing Software!

Since it's summer and my school won't start until September, I was wondering if any of you could help me with something. I have seen amazing graphics designed by people so I want to try too. I have A LOT of free time. I know Paint Sai and Gimp. I downloaded them on my computer but it got a virus and poof, its dead! So my mom got me another one and I was wondering if any of you could tell me an editing software to download. And tell me if Gimp is better or Paint Sai. Please tell me in comments :) Thanks a lot!

BTW, my computer didn't get a virus because of any of the software, I am totally sure!